Adjustable anchor systems and methods

ABSTRACT

An adjustable anchor system for securing tissue to bone, including an anchor having at least one passage extending from a proximal end toward a distal end. The passage defines a restriction such as a restricted opening. The anchor has at least one bone-engaging feature disposed between the proximal and distal ends. The system further includes a first material formed as a closed loop and capable of being placed through a portion of the tissue, and a second filament having a terminal end, a post limb and a sliding knot tied between the terminal end and the post limb to establish an elongated, adjustable-length loop which extends beyond the proximal end of the anchor and captures the closed loop of the first material. The knot of the second filament is restrained by the restricted opening when tension is applied as desired to the post limb to shorten the elongated loop to draw the tissue toward the anchor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a system and method for securing tissue to boneand more particularly to adjustable tensioning of tissue whicheliminates the need for knot-tying by a user.

2. Description of the Related Art

A common injury, especially among athletes, is the complete or partialdetachment of tendons, ligaments or other soft tissues from bone. Tissuedetachment may occur during a fall, by overexertion, or for a variety ofother reasons. Surgical intervention is often needed, particularly whentissue is completely detached from its associated bone. Currentlyavailable devices for tissue attachment include screws, staples, sutureanchors and tacks. An example of a cannulated suture anchor is providedin U.S. Patent Application Publication No. 2008/0147063 by Cauldwell etal.

There are a number of suture implant systems which proclaim to be“knotless”, that is, to not require a surgeon to tie a knot duringsurgery. Many such systems control tension on tissue by the depth towhich an anchor is driven into bone. U.S. Pat. Nos. 5,782,864 and7,381,213 by Lizardi disclose certain types of suture anchors whichcapture a fixed-length loop of suture. Adjustable loop knotless anchorassemblies utilizing an anchor element inserted into a sleeve aredescribed by Thal in U.S. Pat. Nos. 5,569,306 and 6,045,574 and in U.S.Patent Application Publication No. 2009/0138042.

Suture anchor systems with sliding knots for repairing torn or damagedtissue, especially for meniscal repair, are disclosed in U.S. Pat. No.7,390,332 by Selvitelli et al. and are utilized in the OmniSpan™meniscal repair system commercially available from DePuy Mitek Inc., 325Paramount Drive, Raynham, Mass. 02767. Other suture anchor systems withsliding and locking knots for repairing tissue include U.S. Pat. No.6,767,037 by Wenstrom, Jr.

It is therefore desirable to adjust tension on a tissue after an anchorhas been fixated in bone without requiring a surgeon to tie any knots,especially during arthroscopic procedures.

SUMMARY OF THE INVENTION

An object of the present invention is to enable tension on tissue to beadjusted independently of anchor fixation and without tying any knotsduring the procedure.

Another object of the present invention is to enable tissue tension tobe adjusted after an anchor driver or other delivery instruments havebeen removed from the field of view of the tissue and the anchor.

This invention results from the realization that precise tension can beapplied to tissue independent of fixation of an anchor in bone byutilizing an elongated, adjustable-length loop of a filament, such as asuture, with a sliding knot, such as a bunt line half hitch knot, havinga post limb that can be pulled as desired after the anchor is fixated inbone. As the post limb is pulled, the anchor restrains the knot to holdit in a fixed position and the adjustable loop slides through a closed,preferably fixed-length loop, which passes through the tissue, to drawthe tissue toward the anchor until a desired tension is achieved. Theanchor continues to restrain the knot while the adjustable loop is undertension and thereby assists in locking the knot.

This invention features an adjustable anchor system for securing tissueto bone, including an anchor having at least one passage extending froma proximal end toward a distal end. The passage defines a restrictionsuch as a restricted opening. The anchor has at least one bone-engagingfeature disposed between the proximal and distal ends. The systemfurther includes a first material formed as a closed loop and capable ofbeing placed through a portion of the tissue, and a second filamenthaving a terminal end, a post limb and a sliding knot tied between theterminal end and the post limb to establish an elongated,adjustable-length loop which extends beyond the proximal end of theanchor and captures the closed loop of the first material. The knot ofthe second filament is restrainable by the restriction when tension isapplied to the post limb to shorten the elongated loop to draw thetissue toward the anchor.

In some embodiments, the first material is a first filament. The closedloop of the first filament is substantially shorter in length than theelongated loop of the second filament. In a number of embodiments, thefirst filament has a diameter at least as large as that of the secondfilament. In certain embodiments, the first filament is formed to have alower abrasive property at its surface than that of the second filament.Preferably, the first material is formed from a first suture and thesecond filament is formed from a second suture. In some embodiments, thefirst suture has a composition that is different from that of the secondsuture.

In certain embodiments, the sliding knot is a bunt line half hitch knot.In some embodiments, the passage is defined by at least one inner lumenin the anchor. In another embodiment, the restriction is defined atleast in part by engagement with bone when the anchor is fixated inbone, the passage extends along an exterior surface of the anchortraversing the bone-engaging feature, and the bone-engaging featuredefines at least one channel as part of the passage.

This invention may also be expressed as an adjustable anchor system forsecuring tissue to bone, including an anchor having at least one passageextending from a proximal end toward a distal end, the passage defininga restricted opening. The anchor has a circumference and at least onebone-engaging feature disposed between the proximal and distal ends. Thesystem further includes a first filament formed as a closed loop havingan opening greater than the circumference of the anchor and capable ofbeing placed through a portion of the tissue, and a second filamenthaving a terminal end, a post limb and a sliding knot tied between theterminal end and the post limb to establish an elongated loop whichextends beyond the proximal end of the anchor. The elongated loopcaptures the first filament and is initially substantially greater inlength than the closed loop of the first filament. The knot of thesecond filament is restrainable by the restricted opening when proximaltension is applied to the post limb after the anchor is fixated in thebone to shorten the elongated loop to draw the tissue toward the anchor.

This invention further features a method for securing tissue to bone,including selecting an anchor having at least one passage extending froma proximal end toward a distal end, the passage defining a restriction,and the anchor having at least one bone-engaging feature disposedbetween the proximal and distal ends. The method further includesselecting a first filament formed as a closed loop, and selecting asecond filament having a terminal end, a post limb and a sliding knottied between the terminal end and the post limb to establish anelongated loop capturing the closed loop of the first filament at afirst location and being initially substantially greater in length thanthe closed loop. The method also includes placing at least a firstportion of the closed loop of the first filament through a portion ofthe tissue to be secured so that the first portion forms an openingthrough which the anchor is one of passed and engaged, that is, theanchor is either passed completely through the opening or the firstportion is engaged by the anchor. The anchor is then fixated in bonesuch that the knot of the second filament is restrained by therestriction and the closed loop engages one of the anchor and theelongated loop at a second location. The method further includesapplying tension as desired to the post limb after the anchor is fixatedin the bone to shorten the elongated loop to draw the tissue toward theanchor.

BRIEF DESCRIPTION OF THE DRAWINGS

In what follows, preferred embodiments of the invention are explained inmore detail with reference to the drawings, in which:

FIG. 1 is a perspective view of an adjustable anchor system according tothe present invention having a closed loop and an adjustable loop offilament;

FIGS. 1A, 2 and 3 are schematic cross-sectional views of alternativeanchor systems according to the present invention;

FIG. 4 is a schematic view of a closed loop after it has been pulledthrough a portion of tissue to be secured to bone, which may draw aportion of the adjustable loop with it through the tissue;

FIG. 5 illustrates an anchor being passed through the fixed loop anddirected toward a hole formed in the bone;

FIG. 6 shows the anchor fixated in bone with tension to be applied onthe post limb;

FIG. 7 illustrates the tissue in a desired position under final tensionafter the post limb has been trimmed;

FIG. 8 shows an alternative technique to that illustrated in FIGS. 6 and7 in which the anchor engages the closed loop instead of passing throughit; and

FIGS. 8A-8C show yet other embodiments in which the closed loop has asufficient length to extend from the anchor up to and through thetissue, as illustrated in enlarged view in FIG. 8B, and another,less-preferred embodiment in which the closed loop has been eliminatedand the adjustable loop passes completely through tissue as illustratedin FIG. 8C.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

This invention may be accomplished by an adjustable anchor system forsecuring tissue to bone, including an anchor having at least one passageextending from a proximal end toward a distal end. The passage defines arestriction such as a restricted opening or an occluding element. Theanchor has at least one bone-engaging feature disposed between theproximal and distal ends. The system further includes a first material,such as a first suture, formed as a closed, preferably fixed-length loopand capable of being placed through a portion of the tissue, and asecond filament having a terminal end, a post limb and a sliding knottied between the terminal end and the post limb to establish anelongated, adjustable-length loop which extends beyond the proximal endof the anchor and captures the closed loop of the first material. Theknot of the second filament is restrained by the restricted opening oroccluding element when tension is applied as desired to the post limb toshorten the elongated loop to draw the tissue toward the anchor until adesired tension is achieved.

Adjustable anchor system 10, FIG. 1, has a suture anchor 12, a closed,fixed-length loop 14 of a first material, and a second filament 16having a terminal end 18, a post limb 20, a sliding bunt line half hitchknot 22, and an adjustable loop 24 with loop limbs 26 and 28. In oneconstruction, suture anchor 12 is similar to the cannulated sutureanchor disclosed by Cauldwell et al. in U.S. Patent ApplicationPublication No. 2008/0147063, incorporated herein by reference. Inanchor systems according to the present invention, however, it is notnecessary to have a post-like suture-engaging member or other occludingelement over which one or more sutures or suture limbs pass to serve asa restriction to proximal movement; in many constructions, it issufficient to have a restricted opening 46 to prevent withdrawal of knot22 as discussed in more detail below, particularly in relation to FIGS.1A-3.

Suture anchor 12 has a proximal end 30 and a distal end 32 with opposeddistal arms 34 and 36 defining cut-out 38 between them. Passage 40 is aninner lumen which runs from proximal end 30 to distal cut-out 38.Although knot 22 is shown extending beyond cut-out 38 in FIG. 1 forpurposes of illustration, knot 22 preferably is seated againstrestricted opening 46 between arms 34 and 36, or otherwise maintained atthe distal end 32 by a cavity or other feature, during insertion ofanchor system 10 into a patient to minimize interference by the knot 22with the bone-engaging feature 42, or other exterior surface of anchor12, and the bone in which suture anchor 12 is fixated.

One or more bone-engaging features 42, such as the helical threadillustrated in FIG. 1 or other features such as teeth, ridges, or otherprotrusions, are formed on the exterior of anchor 12 to enhance fixationin bone. In one construction, the suture anchor rotates to toggle intobone at its proximal end to minimize withdrawal. In a number ofconstructions, a hole is formed in bone prior to anchor insertion; inother constructions, a suture anchor is inserted directly into bone.

One or more passages or channels may be formed on the exterior of thesuture anchor, such as channel 44 illustrated in phantom, FIG. 1,traversing bone-engaging element 42. Other configurations areillustrated in FIGS. 1A, 2 and 3 for adjustable anchor systems 10 a, 10b and 10 c, respectively, according to the present invention, havingfirst, fixed-length loops 14 a, 14 b, 14 c and second, adjustable lengthfilaments 16 a, 16 b, 16 c, respectively. Anchor 12 a, FIG. 1A, definesan inner lumen 40 a and an external passage 50 extending from the distalend to the proximal end of anchor 12 a. Sliding knot 22 a, formed insecond filament 16 a, is seated against restricted opening 46 a,adjustable loop 24 a extends through passage 40 a to capture closed loop14 a, and post limb 20 a lies within external channel 50 in thisconstruction.

It is a matter of surgeon preference whether a terminal end, such asterminal end 18 a, FIG. 1A, is kept at a length sufficient to lieagainst the exterior of at least one bone-engaging feature 42 a to betrapped against bone during insertion, or is trimmed to a shorterlength. Different examples of terminal end length are provided in FIGS.6-8 below. Further, a restriction such as restricted opening 46 a may bedefined at least in part by engagement with bone when anchor 12 a isfixated in bone to prevent knot 22 a from moving with post limb 20 awhen tension is applied to post limb 20 a as described in more detailbelow for procedures of using an anchor system according to the presentinvention.

Anchor system 10 b, FIG. 2, has at least three external passages orchannels 52, 54 and 56 without any internal passages in thisconstruction. Knot 22 b is maintained at the distal end of anchor 12 bby occlusion 51, defined at least in part by the distal surface ofanchor 12 b, while limbs 26 b, 28 b of loop 24 b lie within passages 52,54 and post limb 20 b of second filament 16 b lies within passage 56. Asdescribed above, occlusion 51 may be defined in part by engagement ofanchor 12 b with bone after fixation.

Anchor system 10 c, FIG. 3, has an internal passage 40 c through whichpost limb 20 c extends from a restricted opening 46 c which holds knot22 c. External passages 58, 60 carry limbs 26 c, 28 c of adjustable loop16 c. Although anchors 12 a, 12 b and 12 c are shown withoutdistal-extending arms in those constructions, in other constructions oneor more such distal extensions or other protrusions are provided,similar in some constructions to Cauldwell et al. cited above or to U.S.Pat. No. 7,381,213 by Lizardi, also incorporated herein by reference. Inyet other constructions, a cylindrical or otherwise circumferentialcavity, bowl or countersink feature is provided at the distal end of theanchor to seat the knot 22 during insertion and fixation.

In preferred constructions, loop 14, also referred to as a firstfilament, and second filament 16 are formed of one or more types ofsutures. Acceptable diameters for second filament 16 include size 0 orsize 2 suture, such as Orthocord™ suture commercially available fromDePuy Mitek, while the same or larger diameters such as size 2 to size 5suture are preferred for loop 14, such as Ethibond™ suture availablefrom Ethicon. Orthocord™ suture is approximately fifty-five tosixty-five percent PDS™ polydioxanone, which is bioabsorbable, and theremaining percent ultra high molecular weight polyethylene, whileEthibond™ suture is primarily high strength polyester. In someconstructions, especially for shoulder repair procedures, loop 14 has afixed length of approximately one inch while adjustable loop 24 has alength of at least eighteen inches. The amount and type of bioabsorbablematerial, if any, utilized in the first or second filament is primarilya matter of surgeon preference for the particular surgical procedure tobe performed.

While the same type of suture can be used for both loop 14 and filament16, a suture having a lower abrasive property at its surface ispreferred for the first material forming closed loop 14. The lowerabrasive property can be achieved by a larger diameter, a softercomposition, a softer braid, plait or strand pattern, or a combinationof such characteristics. In some constructions, the suture material forclosed loop 14 is tied with a fixed knot to form the fixed-length loop14. In other constructions, loop 14 is molded or otherwise formed as aring of material.

Slidable knot 22 has been described as a bunt line half hitch knot insome constructions, but other suitable knots will be readily apparent tothose of ordinary skill in the suture tying art after reviewing thepresent invention. The term “slidable” as used herein is intended toinclude slidable, lockable knots as well as slidable knots. Severaltypes of suitable knots are described in the Arthroscopic Knot TyingManual (2005) available from DePuy Mitek, as well as in U.S. Pat. No.6,767,037 by Wenstrom, Jr.

One procedure according to the present invention for utilizing acannulated anchor system similar to that shown in FIG. 1 is illustratedin FIGS. 4-7 for attaching tissue 68 to bone 80. Reference numeralsutilized to describe the system shown for this procedure follow thenumerals utilized for system 10, FIG. 1, for simplicity and clarity,although a number of other types of anchors with different filament limbarrangements as illustrated in other Figures could also be utilized in asimilar manner. An initial suture 70, FIG. 4, having a needle 72 at itsdistal end is passed through tissue 68 to draw at least closed loop 14at least partially through tissue 68. Alternatively, a suture passinginstrument is inserted through tissue 68 to grasp the closed loop 14 andpull it through the tissue 68. The extent to which elongated, adjustableloop 24 is drawn through tissue 68, and whether an anchor passes throughor engages the closed loop 14 or adjustable loop 24, are described inmore detail below relative to FIGS. 8-8C.

In this procedure, a hole 82, FIG. 4, is formed through compact layer 84into cancellous layer 86 of bone 80 at a desired repair location. Anchor12, FIG. 5, is passed through an opening 89 in closed loop 14 asindicated by arrows 90 and is fixated in bone as shown in FIG. 6.Preferably, post limb 20 is extracted from the closed loop 14 afteranchor 12 passes through the opening 89 in closed loop 14, FIG. 5, sothat post limb 20 can pull directly one of adjustable loop limbs throughthe knot 22 without being constrained by closed loop 14. Terminal end 18is trapped between bone 86 and a portion of distal end 32 of anchor 12in this construction, and sliding knot 22 is held by a restrictedopening in internal lumen 40. Alternatively, terminal end 18 has asufficient length so that it extends proximally along the exterior ofthe anchor 12 past a plurality of bone engaging features 42 asillustrated in phantom as length 18 d, or is a shorter length 18 e asshown in FIG. 8.

After fixation of anchor 12, FIG. 6, proximal tension is applied to postlimb 20 as indicated by arrow 92. As post limb 20 is moved proximally,adjustable loop 24 readily slides through closed loop 14 as limbs 26 and28 are shortened. Tissue 68 is thereby drawn toward anchor 12 until afinal desired position, under desired tension, is achieved as shown inFIG. 7. Closed loop 14 engages the elongated loop 24 at first and secondlocations 96 and 98.

Other systems and methods according to the present invention are shownin FIGS. 8-8C as alternatives to the final configuration shown in FIG.7. Terminal end 18 e, FIG. 8, is intentionally short so that it is nottrapped between the anchor 12 and bone 80. In this construction,terminal end 18 e remains within the bone hole 82 and is not placedunder tension of any type.

Instead of requiring an opening 89, FIG. 5, in closed loop 14 to begreater than the circumference of the anchor 12 so that anchor 12 canpass completely through the closed loop 14, in other constructions thedistal end 32 engages a portion of the closed loop 14 as shown in FIG.8. Filament engagement can be accomplished such as shown in FIGS. 11 and12 of U.S. Pat. No. 7,381,213 by Lizardi. However, one benefit achievedby the present invention is that further tensioning of tissue 68 ispossible after anchor fixation by pulling on the post limb of theadjustable loop. Another benefit of the present invention is that theanchor inserter or driver and related driver instruments are removedprior to final tensioning and positioning of the tissue to be repairedto provide improved visual and tactile feedback to the surgeon.

Other arrangements of filaments are illustrated in FIGS. 8A-8C. Anchor12, FIG. 8A, engages filament portion 118 which passes through tissue 68to emerge at the other, proximal side in the circled region indicated at100. In the construction shown in FIG. 8B for that circled region 100,adjustable loop 124 passes through a portion of closed loop 114. Inother words, the same filament limbs form portions 114 and 118 of asingle closed, fixed-length loop. This arrangement is preferred becausethe limbs of adjustable loop 124 are able to slide over the closed loopfilament at location 116 without passing through tissue as adjustableloop 124 is reduced in size.

In contrast, limbs of adjustable portion 124 pass through tissue 68 inFIG. 8C, which represents an alternative configuration for FIG. 8A, andthe adjustable limbs emerge to form portion 118 which is engaged by thedistal end 32 of anchor 12. In other words, no closed loop is utilizedin the configuration represented by FIG. 8C. However, eliminating thefixed-length loop is less desirable because the adjustable loop may tendto lock on itself, and may bind with or cause damage to the soft tissuethrough which it passes. The adjustable loop may be prone to locking onitself even if the anchor is passed completely through the adjustableloop. Further, adjustability of portion 118, FIG. 8C, may be furtherimpeded by an interference fit with bone, unless the limbs of portion118 are properly aligned in channels or other exterior passages alonganchor 12.

Thus, while there have been shown, described, and pointed outfundamental novel features of the invention as applied to a preferredembodiment thereof, it will be understood that various omissions,substitutions, and changes in the form and details of the devicesillustrated, and in their operation, may be made by those skilled in theart without departing from the spirit and scope of the invention. Forexample, it is expressly intended that all combinations of thoseelements and/or steps that perform substantially the same function, insubstantially the same way, to achieve the same results be within thescope of the invention. Substitutions of elements from one describedembodiment to another are also fully intended and contemplated. It isalso to be understood that the drawings are not necessarily drawn toscale, but that they are merely conceptual in nature. It is theintention, therefore, to be limited only as indicated by the scope ofthe claims appended hereto.

Every issued patent, pending patent application, publication, journalarticle, book or any other reference cited herein is each incorporatedby reference in their entirety.

What is claimed is:
 1. An adjustable anchor system for securing tissueto bone, comprising; an anchor having at least one passage extendingfrom a proximal end toward a distal end, the passage including arestriction formed distally of the proximal end of the anchor, and theanchor having at least one bone-engaging feature disposed between theproximal and distal ends; a first material formed as a closed loop andcapable of being placed through a portion of the tissue; a secondfilament having a terminal end, a post limb and a sliding knot tiedbetween the terminal end and the post limb to establish an elongated,adjustable-length loop which extends beyond the proximal end of theanchor and captures the closed loop of the first material; and the knotof the second filament being located such that a portion of the anchoris disposed between the knot and the first material, with the knotlocated at a distal portion of the anchor and the first material locatedproximal of the proximal end of the anchor, the knot being restrainableby the restriction when tension is applied to the post limb to shortenthe elongated loop to draw the tissue toward the anchor.
 2. The anchorsystem of claim 1 wherein the first material is a first filament.
 3. Theanchor system of claim 2 wherein the closed loop of the first filamentis substantially shorter than the elongated loop of the second filament.4. The anchor system of claim 2 wherein the first filament has adiameter at least as large as that of the second filament.
 5. The anchorsystem of claim 2 wherein the first filament is formed to have a lowerabrasive property at its surface than that of the second filament. 6.The anchor system of claim 1 wherein the first material is formed from afirst suture and the second filament is formed from a second suture. 7.The anchor system of claim 6 wherein the first suture has a compositionthat is different from that of the second suture.
 8. The anchor systemof claim 1 wherein the sliding knot is a bunt line half hitch knot. 9.The anchor system of claim 1 wherein the passage is defined by at leastone inner lumen in the anchor.
 10. The anchor system of claim 1 whereinthe restriction is defined at least in part by engagement with bone whenthe anchor is fixated in bone.
 11. The anchor system of claim 1 whereinthe passage extends along an exterior surface of the anchor traversingthe bone-engaging feature, and the bone-engaging feature defines atleast one channel as part of the passage.
 12. The anchor system of claim1, wherein the at least one passage extends through a whole length ofthe anchor from the proximal end to the distal end.
 13. The anchorsystem of claim 1, wherein the anchor has a channel extendingtherethrough, the post limb being disposed through the channel.
 14. Anadjustable anchor system for securing tissue to bone, comprising; ananchor having at least one passage extending from a proximal end towarda distal end, the passage defining a restricted opening, the anchorhaving a circumference and the anchor having at least one bone-engagingfeature disposed between the proximal and distal ends; a first filamentformed as a closed loop having an opening greater than the circumferenceof the anchor and capable of being placed through a portion of thetissue; a second filament having a terminal end, a post limb and asliding knot tied between the terminal end and the post limb toestablish an elongated, adjustable-length loop which extends beyond theproximal end of the anchor, the elongated loop capturing the firstfilament and being initially substantially greater in length than theclosed loop of the first filament; and the knot of the second filamentbeing located such that a portion of the anchor is disposed between theknot and the first filament, with the knot located at a distal portionof the anchor and the first filament located proximal of the proximalend of the anchor, the knot being restrainable by the restricted openingat a position distal to the proximal end of the anchor when proximaltension is applied to the post limb after the anchor is fixated in thebone to shorten the elongated loop to draw the tissue toward the anchor.15. The anchor system of claim 14 wherein the first filament is formedfrom a first suture and the second filament is formed from a secondsuture.
 16. The anchor system of claim 15 wherein the first suture has acomposition that is different from that of the second suture.
 17. Theanchor system of claim 15 wherein the sliding knot is a bunt line halfhitch knot.
 18. The anchor system of claim 14 wherein the passage isdefined by at least one inner lumen in the anchor.
 19. The anchor systemof claim 14, wherein the at least one passage extends through a wholelength of the anchor from the proximal end to the distal end.
 20. Theanchor system of claim 14, wherein the anchor has a channel extendingtherethrough, the post limb being disposed through the channel.